The following patch fixes
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=82338
The patch was bootstrapped and tested on x86-64.
Committed as rev. 253259.
Index: ChangeLog
===================================================================
--- ChangeLog (revision 253298)
+++ ChangeLog (working copy)
@@ -1,3 +1,8 @@
+2017-09-29 Vladimir Makarov <vmaka...@redhat.com>
+
+ PR rtl-optimization/82338
+ * lra-constraints.c (inherit_in_ebb): Check usage_insns check.
+
2017-09-29 Alexander Monakov <amona...@ispras.ru>
* genmodes.c (calc_wider_mode): Suppress qsort macro.
Index: lra-constraints.c
===================================================================
--- lra-constraints.c (revision 253298)
+++ lra-constraints.c (working copy)
@@ -6219,6 +6219,7 @@ inherit_in_ebb (rtx_insn *head, rtx_insn
&& ((cheap = XEXP (cheap, 0)), true)
&& (regno = REGNO (cheap)) >= FIRST_PSEUDO_REGISTER
&& (hard_regno = reg_renumber[regno]) >= 0
+ && usage_insns[regno].check == curr_usage_insns_check
/* If there are pending saves/restores, the
optimization is not worth. */
&& usage_insns[regno].calls_num == calls_num - 1
